Your pedal foot rests are interesting to me since I have been contemplating extra wide pedal cranks that are mostly for appearance (to look like a functional pedal bike with chain to the rear wheel and all), but are really just movable foot rests.
I laid out parts from a standard Schwinn one piece crank, cut each arm and made up doglegs to widen the whole thing to accommodate a fatty engine. This nut job is for the "kindalikeawhizzer" build with a fatboy 5 horse Tecumseh engine. The thing is, the doglegs are copper pipe elbows. No, I wouldn't stand on it. Ha! And no, I wouldn't even try to pedal it, but I wouldn't pedal it anyway, being semi crippled in the first place and the bike being a heavy weight in the second. About a month ago I shared the idea and below photos with fasteddy and Tinsmith. Neither were impressed. I may still do it as a kind of working/dummy crank until such time that someone can use an oxy torch and do some bending on a one piece extra wide crank (which isn't wide enough as is).
I would drill and bolt the pieces together. In the second photo the top crank is the only extra wide one piece crank available. Nice, but not wide enough. You can see how much wider the dogleg version is.
SB